From Wildlife Extra:
Tiny tag reveals record-breaking bird migration
January 2014: A tracking device, which weighs less than a paperclip, has helped scientists uncover one of the world’s great bird migrations.
It revealed that red-necked phalaropes in Shetland migrate thousands of miles west, across the Atlantic to the Pacific Ocean; a journey never recorded for any other European breeding bird.
In 2012 the RSPB, working in collaboration with the Swiss Ornithological Institute and Dave Okill of the Shetland Ringing Group, fitted individual geolocators to ten red-necked phalaropes nesting on the island of Fetlar in Shetland, in the hope of learning where they spend the winter.
When the birds returned to Shetland experts discovered it had made an epic 16,000 mile round trip – from Shetland across the Atlantic, south down the eastern seaboard of the US, across the Caribbean, and Mexico, ending up off the coast of Peru. After wintering in the Pacific, it returned to Fetlar, following a similar route.
The red-necked phalarope is one of the UK’s rarest breeding birds. It is now only found in Shetland and the Western Isles, and numbers fluctuate between just 15 and 50 nesting males.
Malcie Smith of the RSPB said: “To think this bird, which is smaller than a starling, can undertake such an arduous journey and return safely to Shetland is truly extraordinary. This tiny tracker has provided a valuable piece of the puzzle when building a picture of where phalaropes go when they leave our shores. We hadn’t realised that some Scottish birds were travelling thousands of miles to join other wintering populations in the Pacific Ocean.”
See also here.
An explanation for the Red-necked Phalarope population crash at Bay of Fundy staging site in 1980s: here.